Research On Robust Control Strategy For High Rise Elevator Vertical Motion

The control system of high-rise high speed elevator is a multi-variable, multi-performance index, uncertainty, time-varying and nonlinear large-scale complex control system, which involves mechanical, electrical transmission, control and optimization interdisciplinary theoretical issues. For the questions that robust trajectory tracking, re-leveling and ride quality of vertical motion of high-rise high-speed elevator under the constraint of crash time with uncertainty, theoretical research is presented in this dissertation. The theorety and implement methodology which is researched is the key technology of achieving localization of high-rise high-speed elevator.In this dissertation, considering the vertical dynamic characteristics of high-rise elevator, some factors such as uncertain factors of rope stiffness and dynamic damping, appearing during the change of time and space, affects on the whole system in the car dynamics process. The dynamic model of elevator system based on lumped parameter is proposed approximation to capture the finite force transmission delay characteristics in hoist rope and compensation rope. For the question that complete mathematical model based on lumped parameters for the elevator that the order of the interaction among multi-state variables result in low reliability of numerical simulation of control algorithm, the three degree of freedom (3 DOF) designed model with 6 state variables is established to describe the high-precision dynamic characteristics of elevator.To solve the problems that trajectory tracking and re-leveling control performance of the elevator control system can not be simultaneously optimal for one degrees of freedom control, the two degrees of freedom robust control strategy applied to elevator control, which H∞control is integrated with two degrees of freedom control is proposed. According to H∞feedback control theory, output feedback controller is designed to ensure system stability and strong ability of restraining disturbance. A robust feedforward controller is designed to improve the system output tracking accuracy, ensuring the accuracy of the trajectory tracking and re-leveling to parametric uncertainty in the system. Based on in-depth study of T-S fuzzy system, it is proposed that the fuzzy control strategy based on generalized Takagi-Sugeno (T-S) fuzzy model with uncertain parameters, and dynamic parallel distributed compensation (DPDC) controller are proposed to achieve non-linear compensation in the high-rise elevator motion control. The linear matrix inequalities (LMIs) are used to systematacially solve multi-objective control problems. For nonlinear problem of high-rise elevators dynamic systems, considering the nonlinear system characteristics effectively descripted by T-S fuzzy model, T-S fuzzy model with uncertain parameter of the dynamic elevator system is established, for that local state feedback controllers by using DPDC principle to attain sufficient condition to be asymptotically stability of closed-loop system and satisfy the H∞performance indexes. For high-rise elevator motion control that is typical multi-objective control problem, convex optimization techniques based on LMIs once complete asymptotic stability judgement to get the state feedback gain matrix that meet performance indexess such as trajectory tracking, re-leveling, ride quality, run-time and robustness. By comparing simulation and experimental study, the proposed control strategy of robust 2DOF and DPDC fuzzy based on generalized T-S fuzzy model with uncertain parameters is verified feasible and effective.